This is what I would like as well but theoretically it should actually be very easy to put together. You just need to merge a legendary player database with a World League database that somebody else has already put together. The key thing is that the player database must only have changes to players and mustn't have any changes to the clubs. I tried this with another legends database but failed because the clubs had been fiddled with.
I'm really keen on this idea because it would make a really tough challenge. Once you win the Champions League with a small club it's difficult to get enthusiastic about a new save.
In any case I think you're doing fantastic work here.